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Reprinted with permission of Rabbi Blech. Originally published in the Orthodox Union Daf Hakashrus, April 1994

Modern Food Technology and Kashrus are intimately connected. Many ingredients and processes commonly used today to manufacture food didn't even exist 50 years ago, and their Kashrus implications must now be addressed. A good example would be the use of industrial enzymes. Enzymology, and related fields of biotechnology, is among the fastest growing and innovative fields of food production. It is therefore incumbent upon those responsible for Kosher food production to understand their use and how they effect Kashrus according to Halacha (Jewish Law).

What is an Enzyme?

An enzyme is a protein produced by a living organism that functions as a biological catalyst. All organisms - animal, vegetable, or microbial (bacterial, fungal, yeast, and mold) produce enzymes to aid in the performance of specific chemical reactions necessary for the life of that organism. The Greeks recognized that there were certain properties in leaven that caused chemical changes converting flour and water into bread. Zymase (Greek for leaven) yielded the concept of zymase, the enzyme mix produced by the yeast in leaven. The word enzyme means "in leaven", and remains the term by which we refer to this class of biological catalysts.

Food technologists have discovered that if we can isolate specific enzymes produced by certain organisms, they can be used to catalyze certain chemical reactions desired in the food industry. For example, a kernel of grain such as barley is composed of an endosperm (predominantly starch) and a germ, both covered by a layer of bran. This kernel was created to be planted and then grow into a new barley plant (see Genesis 1:11). The living part of the seed is the germ, which lies dormant until it is planted where it comes into contact with water and germinates and begins growing. The living germ needs nourishment, which the nascent germ finds adjacent to it in the form of starch in the endosperm. These nutrients, however, are not biologically available to the germ – the germ cannot digest the long chains glucose which form the starch molecule. The germ knows this, and it secretes amylase enzyme to break the starch into smaller units of glucose and maltose that it can then digest.

Many years ago, it was recognized that if one soaked barley in water and allowed it to germinate, a sweet syrup could be extracted from the barley – even though the native barley was not sweet at all! This process is known as malting, and malted barley produces malt syrup. It was also noted that the malted barley could be used as an aid in the fermentation of other grains by breaking the starches down into more easily fermentable sugars. It has now understood that it is the enzymes in the malted barley that break the grain (starches) down into glucose or maltose. This is just one basic example of enzymatic activity used in the food industry.

How Enzymes Are Used

Enzymes are categorized by the substrate that they effect. The modern terminology employed to reflect these categories is to take the name of the substrate and add an "-ase' suffix. For example, the Greek word for starch is amylon, so the enzymes that degrade starches are called amylases. Enzymes that degrade proteins are called proteases, those that degrade fats (lipids) are called lipases, etc. The older system for naming enzymes used an -in" suffix, such as papain, rennin, pepsin, bromelain, etc. You will also note that almost all enzymes used in food preparation degrade the substrate, that is they break the food into smaller units. Starch is broken down into dextrins and sugars, sucrose is split (inverted) into glucose and fructose, and casein is coagulated into cheese. A notable exception to this is glucose isomerase, which actually reconfigures a glucose molecule into a fructose molecule.

The following is a list of some commonly used enzymes and their applications in food manufacture:

Alpha Amylase - Degrades starch into dextrin. Used in the manufacture of corn (glucose) syrup, alcohol fermentation , and in bakery products

Glucoamylase - Degrades dextrin into glucose

Glucose Isomerase - Changes glucose into fructose. Used to make High Fructose Corn syrup (HFCS).

Rennin - The primary enzyme in rennet. Used to make cheese by breaking down and destabilizing the casein molecules.

Lipase - Used to enhance buttery flavors in oils by degrading some of the lipids.

Protease - Degrades proteins. Used to chillproof beer (remove the protein haze in cooled beer), tenderize meats, and to age cheese (Enzyme Modified Cheese –EMC). It is also used in the baking industry to act as a dough conditioner.

Pectinase - Used in the fruit juice industry to break down pectin.

Cellulase - Also used in the fruit juice industry as a pressing aid to break down the cellulose in the fruit.

Catalase - Used to degrade hydrogen peroxide (H2O2). H2O2 is added to eggs and dairy products to aid in pasteurization, and is subsequently removed by adding catalase.

Glucose Oxidase - Used to degrade sugars, such as in dried egg whites. If the sugar would remain the dried egg whites, it would caramelize during the heat treatment to which the powdered eggs are subjected and give a brown color to the product.

Invertase - Splits the sucrose molecule into its component fructose and glucose. Used in the confectionery industry.

Lactase - Allows the body to digest lactose (milk sugar) by degrading it into its component sugars (glucose and galactose).

Trypsin - A primary mammalian protease. Used in some infant formulas to predigest casein.

How are Enzymes Derived?

Enzymes used in the food industry can be derived from three basic sources - animal, vegetable, or microbial. There are three enzymes commonly used in food preparation today that are derived from animal tissue. The enzyme preparation called rennet is an extract of the fourth stomach of a calf, and is rich in the enzymes rennin and pepsin. Both of these are proteases that cause milk to curdle into cheese. Another is lipase, which is used to impart buttery flavors to oils by degrading some of the lipids, and to hasten the aging of cheese ("Enzyme Modified Cheese" - EMC). The use of rennet is discussed in the Talmud and is subject of much discussion amongst the commentaries. Historically, rennet was considered Kosher only when it was extracted from Kosher slaughtered calves, the issue of Basar B'Chalav (the prohibition of mixing milk and meat together) being thoroughly discussed by Rabbinic authorities). [There are various opinions regarding extracting rennet from dried non-Kosher animalstomachs. Lipase derived from non-Kosher animal tissue is similarly prohibited.

Another animal tissue preparation used in the food industry is called pancreatin, which is desiccated pancreatic tissue, generally from swine. It is rich in a plethora of protease enzymes, and is used to modify protein to make it more easily digested. Another such enzyme is trypsin, used for the same purpose. Pancreatic tissue and its derivatives are the ingredients used in Nutramigen, Alimentum, and GoodStart infant formulas to break down the protein for children who cannot otherwise digest it. [You will also find such ingredients in some so-called health foods designed to increase muscle mass.]

Important: While these infant formulas are not certified as Kosher, the amount of non-kosher enzyme in them is quite small. If a doctor recommends use of such products, a Rabbinic authority should be consulted.

There are three major plant-derived protease enzymes used commercially today. Papain is derived from the papaya plant. Bromelain from the pineapple plant, and ficin from the fig Papain and bromelain are commonly used as meat tenderizers, ficin being more limited in use due to its more dangerous proteolytic activity. Barley amylase is also used to make maltose syrup.

The recent explosion of interest in enzymes involves the third source-microbial. The growth of microorganisms on nutrient media allows these microorganisms to produce varied enzymes as part of their natural metabolic function. This process is commonly referred to as fermentation. For example, in order for a yeast to grow on a starch, it must first excrete a series of amylases to convert the starch into a sugar that it can then digest. If the growth of the microorganism can be manipulatcd in such a way so that the microorganism produces a surfeit of desired enzymes, these enzymes can be harvested and concentrated for use in other applications. This is the heart of enzyme production via fermentation.

The microorganisms used in fermentation (bacteria, fungi and yeast) are naturally occurring and (until recently) the art of enzyme production was limited to discovering and isolating those strains of a microorganism which would produce substantial amounts of specific enzymes under optimum conditions. Over the years various such microorganisms were isolated and grown, with natural mutations of the organisms being observed. Some of the mutations of these microorganisms proved superior in their ability to produce desired enzymes, and they were isolated and propagated. Manipulating the chemical or physical environment of the microorganism (mutagenesis) can also induce mutations. The enzyme companies now have a bank of such microorganisms, and are continually striving to improve the strains.

A more recent advance has been the development of recombinant DNA technology, commonly known as cloning. One way is to identify the genetic code that causes an existing microorganism to produce the desired enzyme, and reproduce it several times within the same organism. The organism is now "supercharged" compared to its normal production of this enzyme. However, scientists have now learned to reprogram microorganisms found in nature with genetic information copied from entirely different organisms, allowing the host organisms to produce enzymes (or other chemicals) which they would originally be incapable of synthesizing. This new organism is one that never occurred in nature, but is now a living reproducing organism with unique qualities.

A good example of these two approaches would be what is commonly referred to as "microbial rennet". Rennin, the major enzyme found in the rennet preparation made from a calf s stomach, is a specific protease enzyme, and is used in the food industry in the way it breaks the casein molecule in milk causing it to curdle and make cheese. Due to the limited amount of animal rennet available, scientists looked for another protease that would function in a manner very similar to rennin. Several strains of microorganisms were identified which, when grown under appropriate conditions, produced proteases which made cheese in a manner very similar (but not identical to ) rennin. These are the "microbial rennets" which we use to make Kosher cheese. Some of the common organisms used for this purpose are Mucor mehei, Mucor pussilus lindt, and Endothia parastica, their rennets known in the industry by the trade names Fromase, Emporase, and SureCurd respectively. The problem with these products is that they are not chemically identical to rennin and they function slightly differently. In addition, these microorganisms produce other enzymes that can impart undesirable flavor characteristics in cheese production. Several companies have now come up with genetically altered microorganisms that have been coded to produce true rennin. These include Chymax, which is produced by a genetically modified strain of E. coli, Chymogen produced from a genetically modified Aspergillus niger, and Maxiren produced from a genetically modified saccharomyces. The advantage of these rennets produced through genetic engineering over conventional microbial rennets is a matter of debate, but the distinction is important.

Halachic Concerns

With the exception of the plant and animal proteases and animal lipases listed above, virtually all enzymes used in food production today are derived through microbial fermentation. Plant proteases, being extracts of plant tissue, usually pose no Kashrus s issues other than the diluant used. Enzymes are very powerful, and they must typically be diluted and standardized to a uniform usable strength. A common diluant is lactose, so one must be careful that papain and bromelain, for example, may be Dairy for this reason. Animal proteases are generally considered not-Kosher (see above reference to rennet made from dried non-Kosher calf stomachs). Lipase derived from animal tissue is similarly considered non-Kosher.

It is the fermentation process of enzyme production that poses an entire series of Halachic issues. A brief discussion of the process is now in order. Microorganisms, be they fungi, bacteria, or yeast are living entities, which are referred to as "cultures". They are isolated from nature and chosen for their desired characteristics, or they are modified using genetic engineering. The organism must then be preserved, which is typically done by freezing. Various chemicals can be used to protect the organism, which are of concern in Kosher certification (see below). For production of the enzyme, the organism is inoculated into a nutrient medium that allows die organism to propagate and develop a sufficiently large population to produce the enzyme efficiently. Since these organisms are living cells, they must be fed a diet that is conducive to their well being. This propagation may consist of growing die organism in flasks of nutrient broth, on an agar surface containing nutrients, or both. When appropriate growth has been achieved, the culture is then added to a large fermentor where it is allowed to grow and produce the enzymes. There are and are two types of such enzyme productions, intracellular and extracellular. Intercellular production means that the organism producers the enzyme within its cell walls, which must then by lysed (broken open) to harvest the enzyme. Extracellular production means that the organism secretes the enzyme through its cell wall as part of its metabolism, and is recovered from the media in which it grows. At the end of the fermentation, certain chemical and filtering processes are used to separate the enzyme from the dead organisms and other waste material, and the enzyme concentrate is then blended with chemical preservatives to make a finished product.

Enzymes are also distinguished in their use between immobilized and non-immobilized enzymes. The definition of a catalyst is that it aids in a chemical reaction but does not become part of it. As such, it should be available for reuse many times. An immobilized enzyme is one in which the active enzyme is attached to an inert substrate, such as a plastic bead and usually placed in a reaction column. The liquid that is to be modified with the aid of the enzyme is passed through this column and comes into contact with this treated plastic bead. Such an arrangement allows for the enzyme to be used for long periods without being replenished. A non-immobilized enzyme is a liquid or powder that is added directly to the product to be modified. Typically, there is no means of recovering this enzyme, so it remains in the finished product.

The primary issue involved in determining the Kosher status of such enzymes is whether or not the media on which the organism is grown must be Kosher. This has been the subject of much discussion in recent years, the "vinegar controversy" being a notable example. It has been argued that these microorganisms can be considered as a Halachic Cow, and just as we are not concerned with a cow's diet when permitting its milk, so too we should not be concerned with the nutrients consumed by the microorganism as it produces an enzyme. The consensus of the Poskim is, however, that the enzyme has the Halachic status of the media on which it was grown. This is similar to the Halachic approach we take when we ferment Chometz into alcohol where we consider the alcohol to be Chometz.

The second issue is one of Ayn Mevatlin Issur L'Chatchila (purposefully nullifying a prohibited substance through dilution). Again, the accepted Halachic position is that a Kosher certified may not be produced with even small amounts of non-Kosher material even if a non-Jewish company is adding minute amounts of this non-Kosher material for its own purposes. As such, we insistthat all ingredients used in the growth process of the microorganism, from the early flask to the final fermentor, as well as those used to recover, stabilize, and preserve the enzyme, must be Kosher. This means that any glycerin used to preserve the organism or defoamers used to aid in the fermentations must be acceptable. Any chemicals added to the finished product for preservation or standardization must also be Kosher,

As far as enzymes certified for Passover are concerned, we must similarly be concerned that any yeast extracts used as nutrients be Kosher. In addition, any glucose or dextrose must be checked to ensure that it is not made from Chometz starch. As far as Kitniyos (legumes) isconcerned, however, the accepted position is that enzyme fermentations of Kitniyos are acceptable, since we consider the enzymes to be Nishtanah (changed), and Kitniyos is certainly no worse that an Issur D'Rabbanan (Rabbinic prohibition).

We read about a brave new world emerging in food science, with the potential of major changes in how we process and produce food. These changes will affect the Kashrus that we are working to protect. By being aware of these issues, we can take the steps necessary to deal with these issues in compliance with our Kosher tradition.